During menstruation, leakage of menses from the vaginal opening is a frequent problem associated with the use of tampons. Leakage occurs when menses flows along the wall of the vaginal cavity, and out the vaginal opening without being absorbed by a tampon. One of the main reasons for the failure of a tampon to absorb menses is due to the physical limitations of the tampon. To be comfortably inserted into the vaginal cavity, the tampon should have a maximum diameter that is less than the diameter of the vaginal opening. To produce tampons with the desired vaginally insertable size, tampon pledgets are generally compressed into a rigid round cylindrical shape. Therefore, unless the tampon expands to contact and absorb the menses flowing along the walls of the vaginal cavity, the menses will exit the vaginal opening.
Tampons which are compressed rely upon the absorption of menses to generate expansion of the tampon. As there is little or no air in the vaginal cavity, expansion is limited to the volume of menses the tampon absorbs. However, expansion of the tampon is less than the volume of menses absorbed by the tampon, as some expansion potential is lost due to menses replacing air in the tampon. Therefore, the tampon expansion needed to provide protection against menses leakage is limited, especially at low levels of menses. Expansion of the tampon occurs in the direction opposite to which the tampon was compressed. For example, tampons that have been compressed in their length dimension expand primarily in a lengthwise direction. To provide the proper shape for insertion, tampons are primarily compressed radially and/or along their width and length dimensions. However, these compression strategies alone do not effectively maximize the expansion of the tampon.
Attempts in the prior art to control the expansion of tampons in the vaginal cavity have relied on tampons that are capable of dry expansion. Such tampons do not depend on the absorption of menses to cause expansion, and can expand within the vaginal cavity when there is little or no menses present in the vaginal cavity. These tampons are often formed from foam materials. The foam material is compressed in an applicator, and upon release from the applicator the material assumes its uncompressed shape within the vaginal cavity. The uncompressed shape of the tampon contacts the vaginal walls, as the diameter of the uncompressed tampon is greater than the diameter of the vaginal cavity. However, the dry expanding tampons also have several disadvantages. One disadvantage is that the dry expanding tampons can irritate the walls of the vaginal cavity, especially if there is little or no menses in the vaginal cavity. The irritation of the vaginal walls is caused by the tampon expanding and adhering to dry areas of the vaginal cavity that do not contain menses. Further, the tampons function as sponges in that they absorb the menses within the vaginal cavity, but when pulled through the vaginal opening they become constricted, which causes the release of the absorbed menses.
In addition, the prior art has tried to control the expansion of tampons to prevent the leakage of menses. Such control allows a portion or portions of the tampon to expand more or less than other portions of the tampon. For example, a tampon may be produced so that the center section of the tampon is capable of greater expansion than other portions of the tampon. These tampons typically restrict the expansion of certain portions according to a pre-determined pattern. For instance, an adhesive or bonding agent may be applied to, or incorporated into, a tampon to selectively prevent a portion of the tampon from expanding to the same degree that another portion expands when the tampon absorbs menses. The restriction in expansion of portions of the tampon has the disadvantage of reducing the amount of menses that the tampon may absorb, reducing the tampon's effectiveness.
What is needed in the art is a tampon that will substantially prevent the leakage of menses from the vaginal opening. Specifically, a tampon that can prevent leakage of menses when flow is at low levels, without causing discomfort to the user, and which overcomes the shortcomings of the tampons in the prior art.